Processing graphics primitives to render images for display is computationally intensive. The latency associated with rendering a frame is a limiting requirement for many applications. For example, real-time image rendering systems may be required to render frames at a minimum of 30 frames per second (fps). When the scene being rendered becomes too complex, then the system may not be able to produce frames at the desired frame rate. Reducing the frame rate results in choppy video that does not appear to a viewer to be high quality. In computer gaming applications, where user input is used to render frames of video, long latency may result in a noticeable lag between a user providing feedback via an input device and the feedback causing a resulting action on the video. This lag is an undesirable trait that is easily noticed by those people playing the game.
Virtual reality systems place a new emphasis on rendering latency. Because the motion of a head mounted display is tracked and utilized to update the generated video, any latency in rendering results in a disconnect between what the user sees in response to the physical motion. When this rendering latency is high, the user may become nauseous due to the disconnect between the visual stimulus and the motion detected by the inner ear.
In order to reduce this effect, virtual reality systems may have higher refresh rates than typical displays. Typical refresh rates may be 60 Hz or higher. However, the rendering latency associated with generating the image frames for display may not enable frames to be generated as these high refresh rates. Thus, there is a need for addressing these issues and/or other issues associated with the prior art.